Biomimetic Oxidations of Xenobiotics by Metalloporphyrin and Salen Catalysts: Recent Applications

The importance of cytochrome P450 enzymes (P450) and their contribution to the majority of xenobiotic phase I metabolism is well established; as such, P450 is the only family of enzymes required by the FDA to be fully evaluated for any interaction(s) with all new chemical entities. The traditional methods used to screen potential therapeutics, generally involving biological systems, present numerous intrinsic issues that have led researchers to explore alternative means. Moreover, the highly selective nature of enzymes has created a type of “gold standard” for catalysis, leading to many attempts to develop systems with similar capabilities, or mimics. The fields of biocatalysis and biomimetic catalysis have grown considerably in the past decade; the objective of this review is to discuss two such catalysts employed in the biomimetic area: metalloporphyrins and metallosalens. These catalysts are often used as P450 mimics, metalloporphyrins in particular, as they are structurally and therefore mechanistically similar to heme B, the activesite common to all P450 enzymes. The focus herein will be on the biomimetic oxidations of compounds that are of biological relevance to humans, ranging from pollutants, to current and potential therapeutics. Additionally, successful applications utilizing metalloporphyrin and salen catalysts for the regio- or enantiospecific oxidation of an advanced intermediate to generate [high-purity] chiral natural products will be briefly discussed.